After President Reagan was shot, night editor Joseph E. Bouchard received seven phone calls from abroad.

Each caller asked, "Was the president wearing a bullet-proof vest?"

When Joe told me about the calls, several thoughts flashed into my mind, in this order:

It appears the president was not wearing a protective vest.

He probably should have been.

The Secret Service should be asked why he wasn't wearing a vest, and does he ever.

Don't ask that question, and even if somebody hands you the information on a silver platter, don't print it. Potential assassins already know too much about how to harm a president.

Protective vests have been vastly improved recently. Can an average citizen buy one? Should he?

To get the answer to the last of those thoughts, I talked to people who sell protective clothing in this area. At Fargo International in Kensington I learned that about a dozen types of protective vests are availabe. Some are relatively thin and are designed to be worn under the shirt. Others are worn outside the shirt and, although visible, can be made to look like "the vest in a three-piece suit." SWAT teams use heavy-duty gear that is less comfortable and not suitable for prolonged street wear.

Prices range from about $130 to $600, depending on price and comfort considerations and "what sort of weapon you're trying to protect against. A light vest would probably stop, a .38, but not a .357 magnum. You'd need a heavier weight ballistic liner for that. It would cost more and might be less comfortable."

Would a light under-the-shirt devise have stopped the .22 bullet that entered President Reagan's chest. "Probably, but not certainly. It would depend on how low the vest was cut under the armpit and where the assailant's bullet struck. There is a trade-off between comfort and protection."

Note: The average citizen cannot walk into the Fargo store and buy these items. Sales are restricted to law officers and "government."

Much of the foregoing was confirmed for me at Philips Police Equipment Co., 931 H St. NW, where I also learned that various types of ballistics liners are designed to be worn next to the skin, over an undershirt, and over a dress shirt. Some liners zip out and are washable, some require dry cleaning.

Some manufacturers forbid sales of their vests to the public, and Philips honors such restrictions. It also imposes restrictions of its own on the merchandise of its own on the merchandise it is permitted to sell to the public. A spokesman said, "We feel we have an obligation to find out who wants the equipment and for what purpose. For example, we have sold quite a bit of protective gear to newsmen who have just been assigned to trouble spots overseas. We sold a vest to a scientist who exposed a scandal and feared for his life as a result. Those are legitimate purposes."

Philips' best customers among civilians are "the wives of policemen, and other women who worry about husbands with dangerous jobs."

The most interesting man I encountered in gathering material for this column was Edwawrd A. (Bob) Coppage, head of Progressive Apparel, 2929 Eskridge Rd., Fairfax. As far as I could ascertain, he is the only person in the country who has developed a full line of other bullet-resistant garments -- shirts, casual jackets, raincoats, overcoats, and even a set of long underwear.

Most so-called bullet-proof vests come in four ready-made sizes: small, medium, large and extra large. Coppage's garments are custom-made in exact sizes, each available in three basic levels of protection or "stopping power."

Most of Coppage's business is done with lawmen and government agencies, not only in this area but around the world. He will sell to a private individual. But only if he can satisfy himself that the customer is a reputable citizen with a demonstrable need for protection. "For example," he told me, "I made a vest for a boy who had lost a kidney and wanted to be able to play basketball without worrying about a flying elbow digging into a sensitive spot. That's a legitimate reason for wanting protection.

Would President Reagan have been well served by the modern protective clothing that is now available? Everybody I talked to thought that even a light under-shirt vest would have kept the president out of the hospital